Date of Award
Doctor of Philosophy (PhD)
Environmental Engineering and Earth Science
Dr. Lindsay Shuller-Nickles
Dr. Brian Powell
Dr. Mark Schlautman
Dr. Rachel Getman
Overall, the objective of this dissertation was to investigate the degree of sorption for the alkali cations on rutile to ascertain the impact of different cation properties, such as ion size and charge density, on sorption mechanics as well as probe how the ion may alter the surface – aqueous interface. Initial molecular dynamic simulations and batch experiments showed minimal surface sorption for any alkali cation at relatively low concentrations while simultaneously suggesting the enthalpy of deprotonation shifts slightly in the presence of the alkali cations at different ionic strengths. The cations are likely causing small reorientations of the near-surface water structure, resulting in a different enthalpy of deprotonation of the surface sites. Further MD simulations demonstrated the sorption trend is reverse lyotropic with more of the smaller cations near the surface throughout the MD simulations relative to the larger cations. Comparisons of different complexation models of the thermograms from isothermal calorimetry showed some imprecision in the current framework of the most descriptive models. Potential alterations to improve the fit will likely need to focus on the near-surface aqueous description, either through variable capacitance values or careful consideration of the differences in water orientation in the stern layer of different crystal surface planes.
Johnston, Isaac, "Computational and Experimental Investigations of Alkali Cation Interactions at the Rutile – Water Interface" (2022). All Dissertations. 3238.